<p>Northern Australia contains extensive Proterozoic-aged sedimentary basins with potential energy, mineral, and groundwater resources concealed beneath the surface. The region is remote and largely underexplored with limited data and infrastructure and therefore is considered to have high exploration risk. Exploration for hydrocarbons and basin-hosted base metals, although perceived to have very different exploration models, share a number of important similarities and key parameters. Foremost amongst these is shale geochemistry since the same reduced, organic-rich shales are both a hydrocarbon source rock and a depositional site for base metal mineralisation. Furthermore, anoxic and euxinic (anoxic with free hydrogen sulfide, H2S) water column and sediments are important for both the preservation of organic matter and as a H2S reservoir needed for precipitation of ore minerals after reaction with oxic metalliferous brines. Here we present new organic and inorganic geochemical datasets for shales in the South Nicholson Basin, Lawn Hill Platform and greater McArthur Basin, including the organic-richness of shales and the inorganic geochemistry of redox-sensitive trace metals, to demonstrate changes in water-column chemistry and favourable base metals depositional sites. Parameters such as total organic carbon (TOC) content and redox-sensitive elemental concentrations are used to identify prospective packages with hydrocarbon and base metals mineral resource potential <p>The results reveal many units in the Lawn Hill Platform, South Nicholson Basin and greater McArthur Basin contain organic-rich rocks. A cut-off value of TOC ≥ 2 wt% is used to define several shale and carbonate sequences in the region that are favourable for both hydrocarbon generation and as base metals depositional sites. Inorganic geochemistry results demonstrate a range of paleoredox conditions, from predominantly anoxic, ferruginous conditions with deviations, to sub-oxic and euxinic conditions. Future work mapping the temporal and spatial distribution of this geochemistry, in combination with other mappable geological criteria, is required to create mineral and petroleum systems models that can define prospective fairways across the basins and increase our understanding of resource potential. <p>The precompetitive data generated in this study highlight the utility of shared geochemical datasets for resource exploration in the region. More broadly, this study improves our understanding of the energy and mineral potential across northern Australia, supporting resource decision-making and investment.

The petroleum systems summary report provides a compilation of the current understanding of petroleum systems for the McArthur Basin, including the prospective Beetaloo Sub-basin. The contents of this report are also available via the Geoscience Australia Portal at https://portal.ga.gov.au/, called The Petroleum Systems Summary Assessment Tool (Edwards et al., 2020). Three summaries have been developed as part of the Exploring for the Future (EFTF) program (Czarnota et al., 2020); the McArthur Basin, the Canning Basin, and a combined summary of the South Nicholson Basin and Isa Superbasin region. The petroleum systems summary reports aim to facilitate exploration by summarising key datasets related to conventional and unconventional hydrocarbon exploration, enabling a quick, high-level assessment the hydrocarbon prospectivity of the region.

The Exploring for the Future program is an initiative by the Australian Government dedicated to boosting investment in resource exploration in Australia. As part of the Exploring for the Future program, this study aims to improve our understanding of the petroleum resource potential of northern Australia. This data release presents the bulk kerogen kinetics of 21 potential source rocks from the McArthur Basin and the Lawn Hill Platform to understand the rate of hydrocarbon conversion. Kerogen was isolated from bulk rock, and analysed by a Rock-Eval 6 (Vinci Technologies, France) using four different temperature ramps. All sample preparation and analyses were carried out in Geoscience Australia’s in-house laboratories. The results of this study can be used to improve our understanding of the hydrocarbon generative potential of Proterozoic aged source rocks in northern Australia.

The ca. 1.4 Ga Roper Group of the greater McArthur Basin in northern Australia comprises the sedimentary fill of one of the most extensive Precambrian hydrocarbon-bearing basins preserved in the geological record. It is interpreted to have been deposited in a large epeiric sea known as the Roper Seaway. Trace element data suggest that the redox structure of the basin was a shallow oxic layer overlying deeper suboxic to anoxic waters along with a prominent episode of euxinia. These anoxic and sulfidic conditions, as inferred by redox sensitive trace element (TE) abundances, (molybdenum, vanadium and uranium), developed due to high organic carbon loading consistent with models that suggest that euxinic conditions cannot develop until the flux of organic matter is significantly greater than the flux of bioavailable iron (Fe³⁺), which permits sulphate reduction to proceed. Considering the high reactive iron and molybdenum contents of these shales and the requirement for S/Fe ratios >2 for euxinia to develop, suggest sufficient atmospheric O₂ was available for oxidative scavenging of S and Mo from the continents. This is further supported by prominent negative cerium anomalies within these shales, indicative of active oxidative redox cycling of cerium. We propose that the high organic matter flux was the result of increased nutrient loading to the Roper Seaway from weathering of the continental hinterland. Data from both major and high-field strength elements (niobium, tantalum, zirconium and, hafnium) together with neodymium isotopes (¹⁴³Nd/¹⁴⁴Nd) indicate that a likely mechanism for this enhanced nutrient delivery was a shift in sedimentary provenance to a more primitive (i.e. mafic) precursor lithology. This switch in provenance would have increased phosphorus delivery to the Roper Seaway, contributing to high primary productivity and the onset of euxinia. This dataset and model serve as a basis for understanding the temporal evolution of the deepest sections of the Roper Seaway and finer scale changes in the environment at this time. <b>Citation:</b> Grant M. Cox, Amber Jarrett, Dianne Edwards, Peter W. Crockford, Galen P. Halverson, Alan S. Collins, André Poirier, Zheng-Xiang Li, Basin redox and primary productivity within the Mesoproterozoic Roper Seaway, <i>Chemical Geology</i>, Volume 440, 2016, Pages 101-114, ISSN 0009-2541, https://doi.org/10.1016/j.chemgeo.2016.06.025.

This presentation comprises information for the Minister to answer the following questions: The minister is looking to build his understanding of the different types of hydrocarbons that come out of the ground (e.g. dry gas, wet gas, condensate, etc.), how are they different and what does that mean for value, ease of production, transport?   Provide some simple diagrams demonstrating the spectrum of hydrocarbon types (e.g. oil to gas), as well as figures demonstrating source rock to hydrocarbon type relationships. Give examples of the molecular structures and difference in composition between condensate, light and mediums oils etc. Use examples from northern Australian basins with a focus on the Beetaloo Sub-basin and the Canning Basin. 25 October 2019

Legacy dataset from the NABRE Project, comprising multi-spectral gamma logs obtained on different drill core in the Mount Isa Province to McArthur Basin regions (Northern Territory and Queensland).

<div>This dataset presents results of a first iteration of a 3D geological model across the Georgina Basin, Beetaloo Sub-basin of the greater McArthur Basin and South Nicholson Basin (Figure 1), completed as part of Geoscience Australia’s Exploring for the Future Program National Groundwater Systems (NGS) Project. These basins are located in a poorly exposed area between the prospective Mt Isa Province in western Queensland, the Warramunga Province in the Northern Territory, and the southern McArthur Basin to the north. These surrounding regions host major base metal or gold deposits, contain units prospective for energy resources, and hold significant groundwater resources. The Georgina Basin has the greatest potential for groundwater.</div><div>&nbsp;</div><div>Geoscience Australia’s Exploring for the Future program provides precompetitive information to inform decision-making by government, community and industry on the sustainable development of Australia's mineral, energy and groundwater resources. By gathering, analysing and interpreting new and existing precompetitive geoscience data and knowledge, we are building a national picture of Australia’s geology and resource potential. This leads to a strong economy, resilient society and sustainable environment for the benefit of all Australians. This includes supporting Australia’s transition to net zero emissions, strong, sustainable resources and agriculture sectors, and economic opportunities and social benefits for Australia’s regional and remote communities. The Exploring for the Future program, which commenced in 2016, is an eight year, $225m investment by the Australian Government. More information is available at http://www.ga.gov.au/eftf and https://www.eftf.ga.gov.au/national-groundwater-systems.</div><div>&nbsp;</div><div>This model builds on the work undertaken in regional projects across energy, minerals and groundwater aspects in a collection of data and interpretation completed from the first and second phases of the EFTF program. The geological and geophysical knowledge gathered for energy and minerals projects is used to refine understanding of groundwater systems in the region.</div><div>&nbsp;</div><div>In this study, we integrated interpretation of a subset of new regional-scale data, which include ~1,900 km of deep seismic reflection data and 60,000 line kilometres of AusAEM1 airborne electromagnetic survey, supplemented with stratigraphic interpretation from new drill holes undertaken as part of the National Drilling Initiative and review of legacy borehole information (Figure 2). A consistent chronostratigraphic framework (Figure 3) is used to collate the information in a 3D model allowing visualisation of stacked Cenozoic Karumba Basin, Mesozoic Carpentaria Basin, Neoproterozoic to Paleozoic Georgina Basin, Mesoproterozoic Roper Superbasin (including South Nicholson Basin and Beetaloo Sub-basin of the southern McArthur Basin), Paleoproterozoic Isa, Calvert and Leichhardt superbasins (including the pre-Mesoproterozoic stratigraphy of the southern McArthur Basin) and their potential connectivity. The 3D geological model (Figure 4) is used to inform the basin architecture that underpins groundwater conceptual models in the region, constrain aquifer attribution and groundwater flow divides. This interpretation refines a semi-continental geological framework, as input to national coverage databases and informs decision-making for exploration, groundwater resource management and resource impact assessments.</div><div><br></div><div>This metadata document is associated with a data package including:</div><div>·&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Nine surfaces (Table 1): 1-Digital elevation Model (Whiteway, 2009), 2-Base Cenozoic, 3-Base Mesozoic, 4-Base Neoproterozoic, 5-Base Roper Superbasin, 6-Base Isa Superbasin, 7-Base Calvert Superbasin, 8-Base Leichhardt Superbasin and 9-Basement.</div><div>·&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Eight isochores (Table 4): 1-Cenozoic sediments (Karumba Basin), 2-Mesozoic sediments (Carpentaria and Eromanga basins), 3-Paleozoic and Neoproterozoic sediments (Georgina Basin), 4-Mesoproterozoic sediments (Roper Superbasin including South Nicholson Basin and Beetaloo Sub-basin), 5-Paleoproterozoic Isa Superbasin, 6-Paleoproterozoic Calvert Superbasin, 7-Paleoproterozoic Leichhardt Superbasin and 8-Undifferentiated Paleoproterozoic above basement.</div><div>·&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Five confidence maps (Table 5) on the following stratigraphic surfaces: 1-Base Cenozoic sediments, 2-Base Mesozoic, 3-Base Neoproterozoic, 4-Base Roper Superbasin and 5-Combination of Base Isa Superbasin/Base Calvert Superbasin/Base Leichhardt Superbasin/Basement.</div><div>·&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Three section examples (Figure 4) with associated locations.</div><div>Two videos showing section profiles through the model in E-W and N-S orientation.</div>

Discovery of mid-Proterozoic (1.8 – 0.8 billion years ago, Ga) indigenous biomarkers is a challenge, since biologically informative molecules of such antiquity are commonly destroyed by metamorphism or overprinted by drilling fluids and other anthropogenic petroleum products. The previously oldest biomarkers were reported from the 1.64 Ga Barney Creek Formation in the McArthur Basin, northern Australian. In this study, we present the discovery of clearly indigenous biomarker molecules from carbonaceous shales of the 1.73 Ga Wollogorang Formation in the southern McArthur Basin, extending the biomarker record back in time by ~90 million years. The extracted hydrocarbons illustrate typical mid-Proterozoic signatures with a large unresolved complex mixture, high methyl-alkane/n-alkane ratios and absence of eukaryotic steranes. Also below detection limits were acyclic isoprenoids, saturated carotenoid derivatives, bacterial hopanes and aromatic hopanoids and steroids. Detected, however, were continuous homologous series (C13-C22) of 2,3,4- and 2,3,6-trimethyl aryl isoprenoids (AI). These breakdown products of aromatic carotenoids are the oldest known biogenic molecules, revealing the activity of phototrophic green (Chlorobiaceae) and purple sulphur bacteria (Chromatiaceae). The compounds provide evidence for at least temporary, very shallow (less than ~20 m) stratification of the McArthur Basin 1.73 Ga ago, supporting models of pervasive anoxic conditions in mid-Proterozoic basins.

The Exploring for the Future Program facilitated the acquisition of major geoscience datasets in northern Australia, where rocks are mostly under cover and the basin evolution, mineral, energy and groundwater resource potential are, in places, poorly constrained. In an effort to support sustainable, regional economic development and build stronger communities in these frontier areas, integration of new and legacy data within a consistent platform could enhance the recognition of cross-disciplinary synergies in sub-surface resource investigations. Here we present a case study in the South-Nicholson Basin, located in a poorly exposed area between the prospective Mt Isa Province and the McArthur Basin. Both regions host major base metal deposits, contain units prospective for energy resources, and hold significant groundwater resources in the overlying Georgina Basin. In this study, we interpret a subset of new regional-scale data, which include ~1 900 km of deep seismic reflection data and 60 000 line kilometres of AusAEM1 airborne electromagnetic survey, supplemented with legacy information. This interpretation refines a semi-continental geological framework, as input to national coverage databases and informs decision-making for exploration and groundwater resource management. This study provides a 3D chronostratigraphic cover model down to the Paleoproterozoic basement. We mapped the depth to the base of intervals corresponding to geological eras, as well as deeper pre-Neoproterozoic superbasin boundaries to refine the cover model. The depth estimates, based on the compilation, interpretation and integration of geological and geophysical datasets, inform the basement architecture controls on evolution of the basin, with several key outcomes: 1) expanded mapped size of the South Nicholson Basin, potentially, increasing prospectivity for hydrocarbons and basin-hosted mineralisation, 2) improved stratigraphic unit correlations across the region, 3) identification of major crustal structures, some of which are associated with mineralisation and springs, and 4) improved basin architecture definition, supporting future investigation of groundwater resources.

The ca. 1.4 billion years (Ga) old Roper Group of the McArthur Basin, northern Australia, is one of the most extensive Proterozoic hydrocarbon-bearing basins deposited in a large epeiric sea known as the Roper Seaway. Black shales from the Velkerri Formation were deposited in a deep water shoaling sequence and are well preserved in the Altree 2 drillcore in the Beetaloo Sub-basin. These shales were analysed to determine their organic geochemical (biomarker) signatures which were used to interpret the microbial diversity and palaeoenvironment of the Roper Seaway. The results were integrated with published inorganic geochemistry and microfossil distributions. The indigenous hydrocarbon biomarker assemblages describe a water column dominated by bacteria with large scale heterotrophic reworking of the organic matter in the water column or bottom sediment. Evidence for microbial reworking includes a large unresolved complex mixture (UCM) and high ratios of monomethyl alkanes relative to n-alkanes—features characteristic of indigenous Proterozoic bitumen. Steranes, biomarkers for single-celled and multicellular eukaryotes, were below detection limits in all extracts analysed, despite eukaryotic microfossils having been previously identified in the Roper Group. These data suggest that eukaryotes, while present in the Roper Seaway, were ecologically restricted and contributed little to the net biomass. The combination of increased dibenzothiophene in the middle Velkerri Formation and low concentrations of 2,3,6-trimethyl aryl isoprenoids throughout the Velkerri Formation suggest that the water column at the time of deposition was transiently euxinic. As a comparison we reanalysed extracts from the 1.64 Ga Barney Creek Formation of the McArthur Basin. The biomarker assemblages differ between the Velkerri and Barney Creek Formations between is a biomarkers and water column chemistry, demonstrating that the microbial environments and water column geochemistry were variable in the Proterozoic.